As is known, rotary-drum laundry driers substantially comprise a substantially parallelepiped-shaped outer box casing; a cylindrical laundry drying tub fixed horizontally inside the casing, directly facing a laundry loading and unloading opening formed in the front face of the casing; a door hinged to the front face of the casing to rotate to and from a work position closing the opening in the front face to seal the cylindrical tub; a cylindrical, perforated-wall, laundry drum housed in axially rotating manner inside the drying tub; and an electric motor for rotating the laundry drum about its longitudinal axis inside the drying tub.
Rotary-drum laundry driers of the above type also comprise a hot-air generator designed to produce and circulate inside the drying tub a stream of hot air with a low moisture level and which flows through the laundry drum to rapidly dry the laundry inside.
In some recently marketed driers, the hot-air generator operates in the same way as a heat pump, and circulates the same air continually inside the drying tub, by continually extracting the surplus moisture from the hot air issuing from the drying tub after flowing over the laundry inside the drum.
Though more energy efficient than driers with an open-circuit, hot-air generator, driers with a closed-circuit, heat-pump-type, hot-air generator have revealed several functional, commercially unpopular drawbacks. A heat-pump-type, hot-air generator, in fact, comprises a large number of component parts—some relatively bulky—that are difficult to accommodate inside the box casing, and which may even take up almost all the space available inside the household appliance, thus making it extremely difficult and expensive to equip the appliance with other performance-improving devices, as in other drier models.
For example, some recently marketed rotary-drum driers with an open-circuit, hot-air generator also feature a pressurized-steam generator which, at the end of the drying cycle, feeds a jet of steam into the drying tub to eliminate or at least greatly reduce creasing of the dried fabrics.
Unfortunately, known pressurized-steam generators are too big to accommodate inside the already crowded box casing of a drier with a heat-pump-type, hot-air generator.